1. Field of the Invention
The present invention relates to technology for printing by forming dots on a printing medium while performing a main scan, and specifically relates to technology for printing images for which there are two types of areas, color areas and monochromatic areas, in the sub-scan direction.
2. Description of the Related Art
In recent years, as computer output devices, there has been a broad popularization of color printers of the type that eject several colors of ink from a head. Among this type of color printer, there are printers that print an image by forming dots on a printing medium by ejecting ink drops from a nozzle while performing a main scan.
Also, there are printing devices that are equipped with a higher number of nozzles that eject only black ink than those for other colored inks. For that kind of printing device, when printing color data, color printing is done using the same number of nozzles for each color. Only the same number of nozzles as the number of nozzles for each color is used for the black nozzles. Then, when printing data that is monochromatic only, the monochromatic printing is performed at high speed using all of the black nozzles.
However, with the printing device noted above, when within the printed image there are two types of areas, monochromatic areas that use only black ink, and color areas, there is the problem that printing cannot be performed efficiently.
Accordingly, an object of the present invention is to efficiently print images for which two types of areas, color areas and monochromatic areas, exist in the sub-scan direction.
To attain at least part of the above and other related objects of the present invention, there is provided a printing apparatus that prints images in a monochromatic area on a printing medium with an achromatic ink alone, and in a color area with chromatic inks, by ejecting ink drops from a nozzle to deposit the ink drops on the printing medium to form dots.
This printing apparatus comprises a printing head having a plurality of single chromatic nozzle groups and an achromatic nozzle group, a main scan drive unit that moves at least one of the printing head and the printing medium to perform main scanning, a sub-scan drive unit that moves at least one of the printing head and the printing medium in a direction that intersects a main scanning direction to perform sub-scanning, and a control unit that controls each of these units (the printing head, the main scan drive unit and the sub-scan drive unit). Each of the plurality of single chromatic nozzle groups consists of plurality of nozzles that are arranged at nozzle pitch kxc3x97D where k is an integer of at least 2 and D is a pitch of main scan lines. The plurality of single chromatic nozzle groups are configured to eject mutually different chromatic inks. The achromatic nozzle group for ejecting achromatic ink consists of a greater number of nozzles that are arranged at nozzle pitch kxc3x97D than each of the single chromatic nozzle groups.
In that apparatus, monochromatic mode printing is also executed by repeating a unit scan operation using all the nozzles of the achromatic nozzle group but without using the single chromatic nozzle groups. The unit scan operation consists of k main scans and (kxe2x88x921) sub-scans of a first feed amount. The unit scan operation in the monochromatic mode printing may be performed such that all dot positions in an achromatic unit band consisting of plural main scan lines without any gap therebetween are serviced by the achromatic nozzle group. A monochromatic mode sub-scan of a second feed amount is performed in each interval between each unit scan operations.
In that apparatus, color mode printing is executed by repeating the unit scan operation using a specific achromatic nozzle group and the plurality of single chromatic nozzle groups while a color mode sub-scan of a third feed amount less than the second feed amount is performed in each interval between each unit scan operations. The specific achromatic nozzle group is part of the achromatic nozzle group.
In specific case in the monochromatic mode printing, a sub-scan of a specific feed amount is preferably performed so that the lowermost main scan line of the achromatic unit band comes to a lower edge of the monochromatic area when the unit scan operation is performed after the sub-scan of the specific feed amount. The unit scan operation is then preferably performed once, while forming dots in the monochromatic area using all nozzles of the achromatic nozzle group. The process is then proceeded to the color mode printing. The specific case is when a lowermost main scan line of the achromatic unit band comes to be positioned within the color area when it is assumed that the monochromatic mode sub-scan and the unit scan operation are performed next, and also that the lowermost main scan line of the achromatic unit band comes to be positioned within the monochromatic area when it is assumed that the color mode sub-scan and the unit scan operation are performed.
For this kind of embodiment, in above specified cases, positioning feed is performed at the end of monochromatic mode printing, and recording of the main scan lines is done using the nozzles of the achromatic nozzle group. If this kind of embodiment is used, in a case such as when the nozzles reach the color area when monochromatic mode sub-scanning is performed, monochromatic area printing can be performed more efficiently comparing to printing for which the printing process shifts directly to color mode printing.
It is preferable that each of the plurality of single chromatic nozzle groups consists of mutually equal numbers of nozzles, and the specific achromatic nozzle group includes a same number of nozzles as each of the single chromatic nozzle groups. By using such an embodiment, it is possible to print images on the printing medium efficiently.
In monochromatic mode printing, it is preferable that the printing process is proceeded to the color mode printing, in the case that the lowermost main scan line of the achromatic unit band comes to be positioned in the color area when it is assumed that the color mode sub-scan and the unit scan operation are performed. If this kind of embodiment is used, it is possible to shift from monochromatic mode printing to color mode printing efficiently.
In specific case in the monochromatic printing, a sub-scan of a specific feed amount is preferably performed so that the lowermost main scan line of the achromatic unit band comes to a lower edge of the monochromatic area when the unit scan operation is performed after the sub-scan of the specific feed amount. The unit scan operation is then preferably performed once, while forming dots in the monochromatic area using all nozzles of the achromatic nozzle group. The printing process is preferably proceeded to the color mode printing. Such procedures are performed in the specific case that main scan line count Lr1 of a remaining monochromatic area is smaller than main scan line count L1 of an achromatic unit band and is larger than main scan line count L2 of a single chromatic unit band. The remaining monochromatic area is an area of the monochromatic area in which dot formation is not completed. The single chromatic unit band consists of plural main scan lines without any gap therebetween for which a one of the single nozzle groups services with a single unit scan operation. By using such an embodiment, it is possible to shorten the time required for printing by performing positioning feed based on simple judgment criteria.
In the monochromatic printing, the printing process is preferably proceeded to the color mode printing in a case that main scan line count Lr1 of the remaining monochromatic area is smaller than the main scan line count L1 of the achromatic unit band and the main scan line count L2 of the single chromatic unit band. By using such an embodiment, it is possible to shift from monochromatic mode printing to color mode printing efficiently without performing complex processes.
In some case, it is preferable that the first feed amount is equal to D, the second feed amount is equal to Nxc3x97Cxc3x97kxc3x97D, and the third feed amount is equal to Nxc3x97kxc3x97D. The case is as follows. The plurality of single chromatic nozzle groups includes C nozzle rows, where C is an integer of at least 2. Each nozzle row includes N nozzles, where N is an integer of at least 2, arranged in the sub-scan direction at the nozzle pitch kxc3x97D. The achromatic nozzle group includes a nozzle row consisting of Nxc3x97C nozzles arranged in the sub-scan direction at the nozzle pitch kxc3x97D. By using such an embodiment, main scan lines recorded by a unit scan operation are adjacent to each other. This makes the process of shifting modes between color mode printing and monochromatic mode printing easy.
In above case, the first feed amount may be equal to mxc3x97D (where m is an integer of 2 or greater that disjoints with k). The second feed amount may be equal to a feed amount for which the sub-scan is performed at a relative position so that the nozzle of the upper edge of the achromatic nozzle group is positioned on the main scan line one below the lower edge of the bundle of main scan lines without any gap therebetween, these being the bundle of main scan lines recorded by the immediately prior unit scan operation. The third feed amount may be equal to a feed amount for which the sub-scan is performed at a relative position so that the nozzle positioned at the very top of the nozzles of the plurality of single chromatic nozzle groups is positioned on the main scan line one below the lower edge of the bundle of main scan lines without any gap therebetween, these being a bundle of main scan lines for which recording is completed by the immediately prior unit scan operation. By using such an embodiment, partial interlace printing is performed, the quality of the printing results increases.
In specific case, it is preferable that the printing process is proceeded to the monochromatic mode printing. The case is that all main scan lines of a color unit band come to be positioned within the monochromatic area when it is assumed that the color mode sub-scan and the unit scan operation are performed next. The color unit band consists of plural main scan lines without any gap therebetween for which an uppermost single nozzle group services with a single unit scan operation.
By using such an embodiment, for color mode printing, by recording both the color area main scan lines and the monochromatic areas together, it is possible to shift from color mode printing to monochromatic mode printing efficiently.
The present invention can be realized in a variety of embodiments such as those shown below.
(1) Printing method and printing control method
(2) Printing apparatus and printing control apparatus
(3) A computer program for realizing the aforementioned device or method
(4) A recording medium on which is recorded a computer program for realizing the aforementioned device or method
(5) Data signals implemented within carrier waves including a computer program for realizing the aforementioned device or method
These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with the accompanying drawings.